1. Technical Field
The present invention relates to a reformer assembly for reforming hydrocarbon such as methane under a presence of steam and particularly relates to a reformer assembly including a plurality of stacked plate-type reformers.
2. Background Art
A lot of fuel cell systems have been developed. The fuel cell system is a power generation system and generally hydrogen is fed to an anode of the fuel cell and oxygen is fed to a cathode of the fuel cell to produce electricity. As the hydrogen is fed to the fuel cell, the hydrocarbon gas such as methane is reformed to a raw material gas for the anode under a presence of steam with a reforming catalyst. The reforming reactions which take place at the just mentioned reformation are: EQU CH.sub.4 +H.sub.2 O.fwdarw.CO+3H.sub.2 EQU CO+H.sub.2 O.fwdarw.CO.sub.2 +H.sub.2
These reactions are endothermic reactions and in order to maintain reforming temperature it is necessary to heat reforming reaction parts.
A conventional plate-type reformer assembly includes reforming plates and combustion plates. The reforming plates and the combustion plates are stacked one after another, thereby defining multiple layers. Generally, the reforming plate is filled with the reforming catalyst and the combustion plate is filled with combustion catalyst. Fuel and air are simultaneously fed to the combustion plates and combusted therein to heat the adjacent upper and lower reforming plates (the combustion plate is sandwiched by the reforming plates). The combustion plate has an entrance and an exit. The reforming temperature of the raw material gas passing through the reforming plates is maintained at a proper level by the combustion in the combustion plates. However, in a case where the fuel and the air are simultaneously fed to the combustion plates, the combustion entirely or mostly takes place near the entrance of the combustion plate and reaches flame temperature. Therefore, a large temperature difference appears between the entrance and the exit of the combustion plate.
Japanese Utility Model Registration Application No. 62-145404 eliminates the above-mentioned drawback. According to an arrangement of this application, a combustion section includes a combustion plate and a dispersion plate. Air is fed to the combustion plate and fuel is fed to the dispersion plate. The fuel fed to the dispersion plate is homogeneously fed into the entire combustion plate. As a result, a homogeneous combustion takes place in the combustion plate and a flat temperature distribution is obtained.
However, in the plate type reformer assembly of Japanese Utility Model Registration Application No. 62-145404, passages for feeding and discharging various gases penetrate the plate type reformers. Consequently, it is necessary to provide adequate sealing between the plates (of reformers) which are stacked one after another.